High tension plug and method of making same



Nov. 10, 1959 A. PALERMO, JR.. ETAL 2,911,683

HIGH TENSION PLUG AND METHOD OF MAKING SAME Filed May 7. 1957 INVENTOR. ANTHONY PALERMO JR.

Y EDWARD B. GRAVES n'onuavs United States Patent HIGH TENSION PLUG AND METHOD OF MAKING SAME Anthony Palermo, In, South Euclid, and Edward B. Graves, Cleveland, Ohio, assignors to Picker X-Ray Corporation, Waite Manufacturing Division, Iuc., Cleveland, Ohio, a corporation of Ohio Application May 7, 1957, Serial No. 657,655

' 3 Claims. (Cl. 18-59) This invention relates to improvements in a high tension electrical plug and a method of making the same. One of the objects of the present invention is to provide a novel high tension electrical end plug for finishing the end of a cable having a plurality of electrical couductors extending longitudinally of the cable inside of an electrically insulating covering, and including a plurality of electrically conducting contact pins, one for each cable conductor, these pins being soldered to their respective conductors and then the cable with the attached pins being inserted into a hollow generally cylindrical plug jacket having at least a partial end wall at one end of the jacket with openings, one for each of the pins. The cable is inserted until the pins extend through the end wall openings and extending beyond the end wall sufiiciently so that the pins will act as electrical contacts when the plug is pushed into a coacting socket or receptacle. The space within the plug jacket around the cable and the soldered end connections is then filled with a flowable and settable electrically insulating compound so that the structure within the plug jacket becomes a unitary whole.

Another object of the present invention is to provide a new method of forming such a high tension electrical cable end plug and comprising the steps of first soldering the contact pins to the individual electrical conductors of the cable, then extending the cable into the plug jacket, forcing the pins through openings in the end wall of the plug jacket in a force fit, and then filling the space within the plug jacket with an epoxy or other similar flowable and settable electrically insulating compound so as to make a unitary structure.

'Otherobjects and advantages of the present invention will be apparent from the accompanying drawings and description and the essential features thereof will be set forth in the appended claims.

.In the drawings Fig. 1 is a perspective view of our invention with portions broken away to more clearly show the interior construction and prior to the filling of the interior of the plug jacket with a flowable and settable electrically insulating compound.

Fig. 2 is a central sectional view through the completed device.

Fig. 3 is an elevational view of the right-hand end of the plug jacket of Figs. 1 and 2 omitting the contact pins for a clearer understanding of the invention; while Fig. 4 is a fragmental perspective view of one end of the electrical cable with three contact pins soldered to their respective electrical conductors in the cable.

This invention is an improvement over a prior device wherein the electrical contact pins were molded in place in the hollow plug jacket in its original form. In this previous device, the short stub ends of the conductors sticking out of the end of the cable each had a fine copper wire soldered to each of the three independent leads. This piece of wire was about a foot long and each of these three fine wires was brought through a tiny hole near the base of its associated contact pin, after which the fine wire was wrapped around and around its associated pin and then this wrapping was worked down into a groove around the base of the pin and subsequently soldered in place there. In this older assembly, there was such a short distance where each of the fine wires was wrapped at one end around the stranded wire cable conductor and soldered there, after which the other end of the fine wire was wrapped around and soldered to the pin as mentioned above, so that the final soldering operation connecting each fine wire to its associated contact pin was likely to heat the first joint where the fine wires were connected to their respective cable conductors. There was also danger of heating the material out of which the plug jacket was made during the operation of soldering the fine wire to each of the contact pins, which sometimes resulted in a loosening of the pins. Unless the final soldering job was done very carefully, the solder would tend to creep up out of the groove around the base of the pin and accumulate on the extending portion of the pin which would be detrimental to the operation of the electrical contacts when the pins were inserted in coacting socket receptacles. It was also difficult in this old device to fill the spaces around the cable and within the plug jacket with the settable and flowable electrically insulating compound.

We obviate these difiiculties by taking the end of the cable 10, scraping away a portion of spaghetti tubing 11 of rubber or the like so as to bare a projecting end 12 of each of the electrical conductors Within the tubing 11. Three electrical contact pins 13 of beryllium-copper or similar suitable material are then provided, each having a recess 1311 at its inner end adapted to receive the bare end 12 of the electrical conductor relatively snugly. Each bare end of the conductor 12 is then soldered into its respective recess 13a in a well known manner. Preferably, but not necessarily, the three pins 13 as shown in Fig. 4 are held in a suitable jig 120 degrees apart around a circle in the same relative position as the three openings 14 in the end wall of the plug jacket 15 which are prepared to receive the contacts. These openings are clearly shown in Fig. 3. v

The plug jacket 15 is preformed prior to preparing the present assembly and is made of a synthetic resin material which sets up substantially rigid. It will be ticed that this plug jacket is generally cylindrical both inside and out. The left end as viewed in Figs. 1 and 2 is open when the jacket is formed and is provided With a flange 16 extending radially outwardly for a purpose later described. The other end, toward the right in Figs. 1 and 2, has a partial end wall formed by means of the inturned flange 1512 which is provided with three bosses 15b degrees apart. The bosses 15b form segments of an end wall. wall. Each of these bosses has a through opening 14 disclosed in the form of apertures which extend longitudinally, generally parallel to the axis of the plug jacket.

This leaves an access or filling opening 17 in the mid-j portion of the partial end wall.

After the pins 13 have been soldered to the conductors 11, as originally described, the cable 10 is inserted into the plug jacket 15 from the open or left end thereof as viewed in Figs. 1 and 2. The pins 13 are arranged to be in approximately the proper position before the cable is entered into the plug jacket. Looking through the opening 17, the operator has no difficulty lining up the 7 pins 13 with their respective openings 14; The pins 13 Thus, the partial end wall is a segmented also, each pin is provided with a series of serrations running generally axially around the periphery of that portion of the pin which fits in the opening 14 and these serrations bite into the synthetic resin material around each opening 14 as the pin is forced into in final position. Preferably also each of the pins 13 has an enlarged shoulder 130 at the inside end thereof so as to limit the outward movement of each pin when it is forced into its receiving opening 14. This insures that the pins 13 will extend a predetermined amount beyond the end wall of the plug jacket 15. The outer end of each pin 13 passes readily through its associated opening 14 and, therefore,

these pins may be pushed through the opening sufiicient- 1y to be grasped by a pair of pliers and pulled forcefully the rest of the distance into the opening 14. Otherwise, one may reach through the space 17.with a suitable tool and press against the shoulder portion 130 to force the pins 13 to their outward final position.

Usually, the high tension cable is provided with an outer protecting casing 18 which may be after the maner of an armoured cable or any other suitable protective covering. To tie this covering into the end connection, a generally frusto-conical ferrule 19 is provided having one end which fits snugly around the insulating cover of the cable 10 and within the casing 18 as clearly Shown in Fig. 1. The opposite end of the ferrule is bent generally outwardly, axially, and then radially inwardly where it is spun over the flange 16 at 19a as clearly indicated in the drawings. A cork gasket is provided at 20 between flange 16 and the ferrule and a neoprene gasket 21 is provided around the base of the plug jacket.

With the parts in the position of Fig. 1, the device is turned in such a position that the pins 13 point upwardly. Then a flowable and settable synthetic resin electrically insulating compound is poured through the opening 17 which passes clear down to the interior of the ferrule 19, fills all the spaces around the cable 10, around the loose ends where the conductors come outthe end of the cable 10 and pass over to the pins 13, and completely fills the inside of the plug up to the level of the outer end thereof as clearly shown in Fig. 2. This material in the present instance is an epoxy resin and is indicated by the reference character 22. This material sets up hard so that the device in its final form as shown in Fig. 2 is a single solitary rigid unit. As further shown in Figure 2 the material 22 is in abutment with the inner ends of the pin 13. This abutment'provides a holding connection between the material 22 and the pin 13 to prevent longitudinal inward movement of the pins relative to the housing 15.

Our improved plug is, therefore, very simple and easy to construct and leaves plenty of room for the entrance of the epoxy resin 22 which is of a soft molasses-like consistence and is difficult to pour through a small opening. Our improved construction gives a large opening at 1'7 which communicates with the spaces around the cable 10 inside of the jacket 15 in a very easily communicable manner.

What is claimed is:

1. The method of making a high tension electrical cable end plug for finishing the end of a cable having a plurality of electrical conductors extending longitudinally within an electrically insulating covering and each conductor having a projecting end extending generally axially beyond the end of said cable, and utilizing a hollow generally cylindrical plug jacket having a greater inside diameter'than the the outside diameter of said cable, and said jacket having a partial end wall extending partially across the hollow of said-jacket at one end thereof, there being a plurality of openings extending through said partial end wall generally parallel to the axis of said jacket; comprising soldering a contact pin to the projecting end of each of said electrical conductors, extending said cable 4 V into the other end of said plug jacket until said pins ext nd xi l y outwardly b y n a ndwa l of saidiackst. closing said other end of said jacket around said cable there, and then pouring a flowable and settable electrically insulating compound into said one plug end having a partial end wall until all spaces around said cable and said projecting ends within said jacket are filled, and setting said. compound. x

2. The method of making a high tension electrical cable end plug for finishing the end of a cable having a plurality of electrical conductors extending longitudinally within an electrically insulating covering and each conductor having a projecting end extending generally axially beyond the end of said cable, and utilizing a hollow generally cylindrical plug jacket having a greater inside diameter than the outside diameter of said cable, and said jacket having a partial end wall extending partially across the hollow of said jacket at one end thereof, there being a plurality of openings extending through said partial end wall generally parallel to the axis of said jacket equal in number to said projecting ends; comprising soldering a contact pin to the projecting end of each of said electrical conductors while holding said pins and projecting ends in a jig in the relative position of said openings in said jacket end, extending said cable into the. other end of said plug jacket until said pins extend axially outwardly beyond said end wall of said jacket, closing said other end of said jacket around said cable there, and then pouring a fiowable and settable electrically insulating compound into said one plug end having a partial end wall until all spaces around said cable and said projecting ends within said jacket are filled, and setting said compound.

3. The method of; making a high tension electrical cable end plug for finishing the end of a cable having a.

plurality of electrical conductors extending longitudinally within an electrically insulating covering and each conductor having a projecting end extending generally axially beyond the end of said cable, and utilizing a hollow gen: erally cylindrical plug jacket having a greater inside diameter than the outside diameter of said cable, and said jacket having at least a partial end wall extending at least partially across the hollow of said jacket at one end there: of, there being a plurality of openings extending through said partial end wall generally parallel to the axis of said jacket; comprising soldering a contact pin to the project: ing end of each of said electrical conductors with each of said pins having a telescoping portion at its end remote from the conductor and having an enlarged head portion between said telescoping portion and conductor, extendsv ing said cable into the other end of said plug jacket with each telescoping portion telescoping in one direction through its opening until said head portion engages the inner surface of said end wall as a stop so that. said pins extend axially outwardly eYOnd said end wall of said jacket, pouring a fiowable and settable electrically insulating compound into the space around said cable, until the space around said cable and said projecting ends and head portions within said jacket are filled, and setting said com-. pound so that the engagement of said compound with said enlarged head portions prevents telescopic withdraw movement of each contact pin in'a direction opposite to said one direction.

References Cited in the file of this patent UNITED STATES PATENTS 2,280,711 Machlett et al. Apr. 21, 1942 2,353,719 Goldfield July 13; 1942;

2,796,743 Landgraf Apr. 19', 19,55

FOREIGN PATENTS 177,610 Great Britain Mar. 31, 1922' 1,062,741 France Dec. 9, i953 

